A microchannel plate has a plate-like structure and has a regularly arrayed structure of a plurality of channels. In recent years, due to expansion in the field of use, widening in the open area ratio and miniaturization of the channels have been required for microchannel plates. With the widening in the open area ratio and miniaturization, due to a misalignment (see FIG. 6) of hexagonal multifibers with each other at the time of manufacturing, a failure of a ring-like connection of channels with each other (a so-called missing wall phenomenon) and a breakage failure of channel walls (a so-called Rosetta phenomenon) easily occur at corners of multifibers adjacent with each other.
As conventional art for solving the above-described problems, disclosed in the specification of U.S. Pat. No. 4,431,694 is a method for preparing, when aligning a large number of standard fibers to fabricate a multifiber, a small number of special fibers having thicker cladding glass tube walls than those of the standard fibers and arranging these at corners of the hexagonal multifibers.